Littelfuse : SM712 series TVS Diode Array Optimized for RS-485 Port Protection – 50% Higher Power Handling Capability


The SM712 series TVS Diode Array (SPA® Diodes) was created for protecting RS-485 applications with asymmetrical working voltages (-7V to 12V) from damage due to electrostatic discharge (ESD), electrical fast transients (EFT), and lightning-induced surges.

The SM712 series can absorb repetitive ESD strikes above the maximum level specified in the IEC61000-4-2 international standard without performance degradation and safely dissipate up to 19A of surge current with very low clamping voltages. This AEC-Q101 qualified device ensures maximum reliability in the harshest environments so it is well suited for industrial applications, including protecting RS-485 ports in equipment such as security systems, Automatic teller machines (ATMs), test equipment, etc.


  • Exceptional power handling capability (600W) with enhanced ESD/surge protection. With 50% higher power handling capability than other industry solutions, the SM712 series gives design engineers more headroom against worldwide regulatory standards.
  • Asymmetrical standoff voltage matches the RS-485 transceiver profile, which ensures data lines are clamped to the lowest possible voltage without interfering with normal circuit operation.
  • Low dynamic resistance (0.5Ω TYP) offers the advanced clamping performance needed to protect modern electronics.
  • Minimal capacitive loading of 75pF (MAX) preserves signal integrity and minimizes data loss over long installations of RS-485 wiring.
  • Automotive-grade quality (AEC-Q101 qualified) ensures maximum reliability in the harshest environments.


  • RS-485
  • Fieldbus
  • Modbus
  • Profibus
  • DMX512
  • Security systems
  • ATMs
  • Automation equipment
  • Communication equipment